Pitting on Thread Drill Pipe

[Salah501]

4" DP looks like they need ~25k EUR in repairs. As rough assumption, it is believed that some Pitting corrosion is involved – your expertise and advice would be highly appreciated. If this prove to be the case, do you recommend to use some corrosion rings in the future (for similar mud system) if required.

 

[Salah501]

my Question again

Recently, we've had a lot of 4” drill pipe rejected as unserviceable during routine inspections due to pitting on the VX39 threads connection. Not sure about the drilling mud chemistry if it’s Oil / Water based. We haven't observed any H2S (not that we know of anyway). I’m not also sure if these joints are lubed every time they make a connection. I just found out about this when I was contacted to look at the pictures. Severe Pitting on the thread, and nose area for the VX39 Pin x Box connections. Any ideas on what could be causing this? I can email a photo of the threads if needed.

 

[redpicker]

Pitting or galling?

Pitting should not occur during use. The connections should have fresh thread dope (lube) applied every time they are made-up. During use (while they are made-up), corrosion cannot occur because the threads are covered with thread dope (a specialized grease with powdered metal added). Corrosion of the threads can only occur during storage. The use of a proper thread storage compound and the correct thread protectors will eliminate corrosion during storage. Bear in mind, that even with a good storage compound and proper thread protectors, stored pipe will need to have the thread protectors removed and the storage compound applied if storage is more than 6 months to a year.

Galling can sometimes look like pitting. Galling is caused by inadequate make-up procedures. Contact a service representative from the manufacturer of the pipe. They should have documentation for proper make-up procedures.

rp

 

[Salah501]

Thanks for your help, It was totally Pitting on the Threads, and on the Nose of the connection fro VX39 type of connections. very good point, that Pitting can not occur while using the pipe.

Much appreciated

 

[EdStainless]

My hunch is that they were not cleaned right away when they were pulled the last time.
This can happen quickly when they are re-exposed to air and moisture.
The systems that I have seen involved the high pressure cleaning, lube, and capping prior to storage.
They did this even if planed reuse was withing a few weeks.

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